Although this topic (ls.st/clo4619) states that diffuse features such as tidal streams or intracluster light were not included in the DC2 simulation, what is the actual threshold? For example, were any faint diffuse nearby galaxies included?
In support science related to weak lensing and deblending, a population of ultrafaint, low-mass galaxies was included in the synthetic sky catalog used to generate DC2, as described in Section 5.1.3 of Korytov et al. (2019). A footnote specifies that their use of the term “ultrafaint” does not refer to “ultrafaint dwarfs” or “ultra-diffuse”, only to the very faint end of their simulated population.
The DESC’s DC2 paper has some relevant text about this ultra-faint population: as “the simulations must extend ~3 magnitudes fainter than the galaxies of interest such that low-luminosity blends are properly included” (Section 2.8), the “catalog also contains many fainter galaxies to magnitude depths of ~33 for use in weak lensing and blending studies. Faint galaxies with r-band magnitudes > 29 are removed from the image simulations to reduce the number of objects that need to be rendered” (Section 5.1).
Supernovae were spatially distributed proportional to host galaxy surface brightness distributions, and so an idea of how faint the low surface brightness edges of the simulated galaxies are can be gleaned from Figure 7 of the DESC’s DC2 paper: from the continuous distribution of surface brightnesses in that figure, it is clear that DC2 contains features at surface brightnesses down to and well below any likely detectable limits (i.e., to >35 mag/arcsec^2).
Further questions or comments about Low Surface Brightness science with DP0 are welcome here as replies in this thread.